The instant invention relates to sulfide terminated oligomers having a backbone of from 2 to 1000 units, in addition to those of the alkyl sulfide moiety, wherein the backbone of the oligomers are made up of hydrophilic acrylamide or substituted acrylamide monomer units or mixtures of such units and copolymerizable hydrophilic and hydrophobic monomer units, and the incorporation thereof into compositions for fire fighting foam, particularly protein hydrolysates.
Foaming agents are effective fire fighting systems for most hazard situations because foams provide great area and volume coverage, blanketing for cooling, sealing of the oxygen source from the fuel, and holding water in place for longer periods of time. To be most effective however, fire fighting foam systems must be stable, they must have a sufficiently high expansion ratio and they must have the ability to move and flow around obstacles.
The most commonly used fire fighting foams include protein foams, fluoroprotein foams, aqueous film forming foams (AFFF) including the special class of alcohol resistant AFFF, and finally synthetic detergent foams (Syndet).
The free radical telomerization of monomers has been recognized since the 1940's as a means of obtaining low molecular weight polymers. Chain transfer agents (telogens) are often added to polymerization recipes as molecular weight regulators to obtain compounds in a molecular weight range not otherwise easily accessible.
In 1946, B. F. Goodrich reported in U.S. Pat. No. 2,396,997 that sulfur containing modifiers, including dodecanethiol, are useful in polymerizing alkyl acrylates or styrene. U.S. Pat. No. 2,878,237 claimed that the molecular weight of acrylamide or acrylic aid could be controlled by mercapto dibasic acids.
Yamashita et al were the first to report the radical telomerization of acrylamide and thiol [Y. Yamashita, et al., Kogyo Kagaku Zasshi (Ind. Chem.), 62, 1274 (1959)]. Later he reported that dodecane thiol could also be used for the anionic telomerization of acrylamide or acrylonitrile [Yamashita, et al. Kogyo Kagaku Zasshi 63, 1746-1751 (1960)].
Subsequently Dannals of Uniroyal claimed the use of various alkyl sulfide telomers as emulsifiers during emulsion polymerization (U.S. Pat. No. 3,498,942), compositions comprised of sulfoxide and alkyl sulfone terminated telomers containing at least one carboxylic group (U.S. Pat. No. 3,668,230), or compositions of alkyl sulfide terminated telomers containing at least one carboxylic group (U.S. Pat. No. 3,839,405).
More recently Henkel has claimed the use of alkyl sulfide telomers of acrylamide (German Patent No. 2,558,591), or cotelomers of acrylonitrile and acrylic acid (German Patent No. 2,558,592), for use in soap compositions suitable for hard water. Alkyl sulfide terminated oligomers of both acrylamide or acrylic cotelomers were also claimed for use in heat exchangers to prevent corrosion and stone deposition (German Patent No. 2,730,645).
German Patent No. 2,745,201 by Arakawa Kagaku Kogyo claims the use of alkyl sulfide, alkyl sulfoxide, and alkylsulfo oligomers for aqueous dispersions of rosin-based materials in paper sizing agents. Finally, Yamada in 1979 [Yukagaku 28, (9) 605-10 (1979)] reports upon the calcium sequestering ability of acrylamide/acrylic acid telomers and suggests their use as sequestrants and metal enzyme models.
Copending U.S. application Ser. No. 129,872 filed Mar. 13, 1980, describes oligomeric fluorinated surfactants of the formula: EQU R.sub.f -E-S-[M.sub.1).sub.x [M.sub.2 ].sub.y H
wherein R.sub.f is a straight or branched chain perfluoroalkyl of 4 to 18 carbon atoms and M.sub.1 and M.sub.2 represent hydrophilic and hydrophobic monomer units. These perfluoroalkyl sulfide terminated oligomers improve foam expansion, foam drainage and extinguishing times as well as reduce the flammability of hydrocarbon contaminated protein foams. Since they contain fluorochemicals they are inherently expensive.